| 1. | An electrical cable of copper has just one wire of radius 9 mm. Its resistance is 5 ohm. This single copper wire of the cable is replaced by 6 different well insulated copper wires each of radius 3 mm. The total resistance of the cable will now be equal to ? | |
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270 ohm
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90 ohm
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45 ohm
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7.5 ohm
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Report Question| 2. | An energy source will supply a constant current into the load if its internal resistance is ? | |
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zero
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non-zero but less than the resistance of the load
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equal to the resistance of the load
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very large as compared to the load resistance
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| 3. | A current passes through a wire of non-uniform cross-section. Which of the following quantities are independent of the cross-section ? | |
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Current density
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Drift velocity
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Free-electron density
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The charge crossing
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| 4. | A strip of copper and another of germanium are cooled from room temperature to 80 K. The resistance of ? | |
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each of these decreases
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each of these increases
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copper strip decreases and that of germanium increases
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copper strip increases and that of germanium decreases
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| 5. | The resistance of a metal increases with increasing temperature because ? | |
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the number of conduction electrons increases
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the number of conduction electrons decreases
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the collisions of the conducting electrons with the lattice consisting of the ions of the metal increase
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the collisions of the conducting electrons with the electrons increase
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| 6. | An electric heater is connected to the voltage supply. After few seconds, current gets its steady value then its initial current will be ? | |
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slightly higher than its steady current
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zero
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slightly less than its steady current
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equal to its steady current
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| 7. | When no current is passed through a conductor, ? | |
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the average velocity of a free electron over a large period of time is zero
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the average speed of a free electron over a large period of time is not zero
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the average of the velocities of all the free electrons at an instant is non zero
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the free electrons do not move
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| 8. | The unit of specific resistance is ? | |
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ohm^-1 m^-1
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ohm^-1
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ohm-meter
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ohm^1
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| 9. | The current density (number of free electrons per m ) in metallic conductor is of the order of ? | |
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10^22
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10^28
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10^26
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10^24
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| 10. | Two or more resistors are said to be in ........... if one end of all resistors is joined together and similarly the other ends joined together ? | |
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parallel
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series
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either (a) or (b)
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None of these
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